Month: August 2013

This week’s fail is an attempt to retrofit a PCB cutting shear with a geared motor. The project was undertaken by [David Cook]. Incidentally he’s very near and dear to us as his book Robot Building for Beginners got us started with hacking in the first place.

This $200 shearing tool is hand-operated and can cut through boards up to 1/16″ thick. But [David] really had to crank on the thing to make a cut. This often resulted in crooked board edges. He decided to do the retrofit in order to achieve higher precision. He sourced a high-torque motor from eBay for around $50 delivered.

We’re hoping that whomever came up with the idea of integrating LEDs into children’s shoes is kicking back on a beach somewhere living off the residuals of the idea. We see those things everywhere. Now the real question is, if you grew up with LEDs in your shoes do you expect cooler light up kicks as you age? [Becky Stern] must think so and that’s why she’s showing off Adafruit’s addressable LED strip shoe project called Firewalker.

This is prototype rather than product, so you can see the Arduino compatible Flora board on the ankle of the lit shoe above. There’s also a battery pack hitching a ride on the laces. But those worried about that fashion faux pas can work on a more finished driver that straps to your calf, or can be integrated in the insole.

Lighting patterns are set off by Velostat, a pressure-sensitive conductive sheet that goes in the heel of the insole. The Flora board measures the resistance, triggering a light show (embedded below) when it drops. Now we just need someone to integrate a power generator based on your movement.

We’re sure that, like us, you’ve heard at least something about Bluetooth Low Energy (BLE). Blutooth 4.0 is another name for BLE and it’s already available in some smartphones; starting with the iPhone 4S, BlackBerry 10, and with Android support added in 4.3 — Jelly Bean. Here’s your chance to get acquainted which what the specification brings to the table. The source material (which we’ll talk about below) provides a ton of background. But if you want a succinct overview check out [Gervasi’s] summary of Bluetooth Low Energy.

We won’t republish the technical details here as both articles do a great job of covering those. Here’s what you should take away from BLE: It’s meant for use with devices running off of a tiny power source. The one outlined in both articles is a coin-cell. But we prefer to think of the future that is energy harvesting. Peak current is limited to 15 mA. This does limit the throughput, but think sensors, not Bluetooth headsets. You just don’t need to push all that much data from these devices. A cleverly designed energy harvesting circuit should be able to implement BLE devices with no battery whatsoever.

[Shea’s] son [Alejandro] was born with Spinal Muscular Atrophy which limits his ability to move. The ability to explore one’s environment as a toddler is really important to development so [Shea] and his wife have been looking into assistive technology. Their health insurance paid for a medical stroller when he was nine-months old and has told the family they need to wait five years for a powered wheelchair. Rather than wait, [Shea] took it upon himself to hack a wheelchair his son could control.

He found a used adult-sized motorized wheelchair on eBay for about $800. Not cheap, but way more affordable than a brand new unit. This type of chair is made to be controlled with a joystick, an option not available to his son at this point. Foot control was an option if he could figure out how to build an interface.

After unsuccessfully trying to repair a broken digital kitchen scale [Shea] was inspired to reuse the sensors as pedal inputs. [Alejandro] has limited foot strength and the sensitive strain gauges are perfect for picking it up. Above you can see the sandal-based interface he built. The two feet working together affect steering as well as forward and reverse. The pedal system is connected to the wheelchair using a Digital to Analog converter chip to stand-in for the original analog joystick. After the break we’ve embedded a video of [Alejandro] exploring the outdoors in the finished chair.

In this case it’s fortunate that [Shea] has the skills to build something like this for his son. We hope this will inspire you to donate your time an know-how to help those in your own community who are in a similar situation. This really takes the concept of The Controller Project to the next level.

We’re starting to become a repository for Arc Reactor replica projects. The one shown above uses mostly laser cut components. We missed it back in May when [Valentin Ameres] tipped us off the first time. But he sent it in again after seeing the 3D printed version earlier this month.

Our biggest gripe is that we don’t have our own laser cutter to try this out on. Everything has been cut from 2mm thick acrylic. The black, silver, and copper colored components were painted to achieve this look. Many of the clear parts also had a dot matrix etched into them to help with light diffusion.

Basic assembly just required the parts be glued together. The finishing touches include wire-wrapping the slots of the outer ring and adding LEDs and current limiting resistors.

The plans are not freely available, but the 3D printed version linked above doubles as a 123D tutorial. That should help get you up to speed designing your own if you are lucky enough to have time on laser cutter.

Check out the resistor color code reference cards I just whipped up. I was inspired by the PCB versions that Octopart has been crowdfunding this week. Those didn’t have the information I would normally be looking up, so I decided to whip up a few of my own and put them out there for inspiration or for you to print yourselves.

The Upverter team loves their FitBit activity tracking devices, but wanted access to raw data. They decided to build their own Open Activity Tracker that would pump data onto an SD card or to a Bluetooth device for processing.

The device uses MPU-9150 motion tracking IC to gather information on movement. This chip combines an accelerometer, gyro, and compass. It also does on-board processing, providing useful data to your host processor over I2C. The only bad news is that it’s a LGA package, which aren’t fun to solder by hand.

The design also has a SD card, Bluetooth module, pressure sensor, and e-ink display. These are all connected to a low power ARM microcontroller.

The team has been webcasting their design sessions, and tonight [Eric Evenchick] (that’s me) will be joining them as they try to cram all of these components onto a PCB. You can watch the live webcast starting at 8:30pm Eastern.